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i SOIL STOCKP><LE SAMPLING Initially, the soil stockpile consisted of approximately 400 cubic yards from the over excavation of T-8 and T-9. On September 8, 1998; Apex collected 16 discreet soil samples from the stockpile (A-1 through A-4, B-1 through B-4, C-1 through C-4, and D-1 through D-4). The soil samples were collected in a grid pattern, so sections of the stockpile could be segregated if necessary. The amount of soil samples collected was based on the County's requirement; one sample per 25 cubic rds. TWs_re uirement was based on our proposal to use this material for final backfilling of <' tank basin T-1 through T-7. Four sections of the stockpile were re-sampled on September 11, 1998 (A-3.1, B-1.1, C-1.1, and D-2.1). Table 2 summarizes the soil stockpile analytical results. All soil stockpile samples were analyzed for: total petroleum hydrocarbons (TPH), as gasoline, TPH, as diesel, by EPA Method 8015 modified; benzene, toluene, ethylbenzene, xylenes (BTEX) and methyl-tert-butyl-ether (MTBE) by EPA Method 8420. RESULTS OF SOIL & GROUNDWATER ANALYSES The analytical results of soil samples collected from beneath the former USTs, and former loading rack are summarized in Table 1. The analytical results of soil samples collected from the . stockpiles are summarized on Table 2. The analytical results of groundwater samples collected from beneath the former USTs and exploratory trenches are summarized in Table 3. All certified analytical data sheets and the chain-of-custody documents are provided in Appendix B. BACKFILLING & REMEDIATION PIPING INSTALLATION BC backfilled the tank basin and trenches east of the office(T-8 and T-9)with clean imported fill. BC backfilled the areas beneath the former loading rack with clean imported fill also. BC backfilled the bottom three feet of tank basin T-1 through T-7 with clean imported-fill. The purpose of backfilling tank basin T-1 through T-7 with clean soil on the bottom of the basin is to prevent groundwater from contacting petroleum impacted soil. The remaining nine feet of the tank basin T-1 through T-7 was backfilled with the remaining stockpiled soil, per County's authorization. While backfilling the remaining nine feet of the tank basin T-1 through T-7, BC spread out this soil in one-foot lifts to allow for maximum aeration of the petroleum impacted soil. After all areas were backfilled to within three feet bg, BC laid out two-inch PVC piping for. possible future remediation. Remediation piping was stubbed out at monitoring wells NM-2, MW-3, the area around former MW-4, and the new eastern dispenser island. Figure 6 shows the location of the remediation piping. RECOMMENDATIONS Based on the soil and groundwater analytical results, Apex recommends performing a subsurface investigation to further evaluate the extent of petroleum impacted soil and groundwater. Apex f proposes to install seven Geo Probes at the site (Figure 7).